A semiconductor layer (channel layer) which is to become a channel portion of a thin-film transistor (hereafter referred to as “TFT”) used in liquid-crystal display devices or organic EL display devices is made of, for example, an amorphous silicon film or a crystalline silicon film (see, for example, Patent Literature (PTL) 1). Here, for example, the semiconductor layer which is to become the channel portion is formed from a crystalline silicon film capable of realizing a TFT having high mobility, compared to an amorphous silicon film. This is because, a high-mobility TFT having a crystalline silicon film as a channel portion can also be used in a high-definition display device in which the size of the TFT is reduced, in addition to the raising of switching speed. As such, in order to manufacture a TFT having a crystalline silicon film as a channel portion, a crystalline silicon film is obtained by forming an amorphous silicon film and subsequently crystallizing the amorphous silicon film, in the manufacturing process.
Well-known methods of crystallizing an amorphous silicon film include, for example, a laser annealing crystallization method, a thermal annealing crystallization method, and so on.